Thermoelectric refrigerating appliances



Nov. 30, 1965 H. MULLER ETAL 3,220,198

THERMOELECTRIC REFRIGERATING APPLIANCES Filed Jan. 16, 1962 3 Sheets-Sheet 1 Nov. 30, 1965 H. MULLER ETAL THERMOELECTRIC REFRIGERATING APPLIANCES Filed Jan. 16, 1962 3 Sheets-Sheet 2 Nov. 30, 1965 H. MULLER ETAL 3,220,198

THERMOELECTRIC REFRIGERATING APPLIANCES Filed Jan. 16, 1962 3 Sheets-Sheet 5 F1914 A-B United States Patent 3,220,198 THERMOELECTRIC REFRIGERATING APPLIANCES Heinz Miiller, Berlin-Charlottenburg, and Fritz Miiller,

Berlin-Waidmannslust, Germany, assignors t0 Siemens- Electrogerate Aktiengesellschaft, Munich, Germany, a corporation of Germany Filed Jan. 16, 1962, Ser. No. 166,504 Claims priority, application Germany, Jan. 19, 1961,

72,113 1 Claim. 7 (Cl. 62-3) Our invention relates to thermoelectric refrigerating appliances and in particular, while not exclusively, to household refrigerators generally of the cabinet type operating with batteries or blocks of Peltier couples as the cold-producing components.

In refrigerating appliances, particularly those for use in kitchens, it is often desirable to subdivide the cooling space in the refrigerator cabinet into a number of compartments of respectively different operating temperatures. For example, it is usually necessary to provide for a normal cooling compartment in which a temperature of about plus C. is maintained. It is further desirable to provide a freezing compartment, such as for the production of ice cubes or preserving frozen-food packages, in which the temperature is to be kept below the freezing point. It is also of advantage to provide another cabinet for a temperature slightly above normal cooling for the purpose of storing or crisping vegetables or preserving butter, for example. In the conventional refrigerators equipped with compression-type refrigerating machines or absorption-type refrigerating systems, the requirement for such compartments of respectively different operating temperatures is met with the aid of a single evaporator by inserting heat insulating partitions or similar means into the cabinet space. It is also known to provide compression-type machines with two evaporators which are supplied with refrigerant from one and the same compressor but are mounted in mutually heat-insulated compartments of the refrigerator cabinet and are so controlled as to maintain different temperatures in the respective compartments. If only one evaporator is used for the above-mentioned purpose, then the necessity for differently adjusting and regulating the temperatures in mutually insulated compartments of the cabinet is difficult and troublesome. Thus it is not reliably feasible to solve the problem in a satisfactory manner and without an excessive maintenance requirement for prolonged periods of refrigerating operation. If more than one evaporator are used, the amount of equipment in the refrigerating system, including the interconnecting refrigerant lines, becomes excessive and unduly increases the cost as well as the space requirements.

Our invention has for its general object to solve the above-described problem in a much simpler and more advantageous manner than heretofore attainable.

Another object of the invention is to afford, without detrimentally affecting the simplicity of design and economy of operation, a subdivision of refrigerating appliances into individual modular units that can be put together or employed in electric connection with one another in any combination that may be desirable at the particular place of installation or employment of the appliance.

Another object of the invention, akin to the one just mentioned, is to readily afford a subsequent enlargement of an existing refrigerating appliance by any desired addition of individual compartments or modular units, all operating from the same electric current supply and permitting in a particularly simple and reliable manner an adjustment to desired temperatures in the subsequently added appliance units.

Still another object related to those mentioned is to afford a better temperature adaptation of individual compartment spaces in the refrigerating appliance to the particular food or type of food to be stored therein and to also provide for a definite aromatic separation of the foods stored in the different compartments of the appliance, to an extent not secured by refrigerating appliances of the type heretofore known.

According to the invention, the refrigerating or cooling appliance is composed of two or more units of which each is equipped with one or more blocks of Peltier couples and which form respectively separate and separately accessible compartment spaces and are adapted to be individually heat-insulated and installable separately from the other units of the appliance. The plurality of thermoelectrically cooled cabinet units, however, are electrically interconnected and provided with one and the same current-supply unit which contains the terminals for attaching the entire refrigerating appliance to the power supply, such as a utility line, and, as a rule, also comprises the rectifying means for converting the line voltage, being normally an alternating voltage, for example of volts and 60 c.p.s., into the low direct voltage needed or preferably for the operation of the Peltier blocks.

Such provision of thermoelectric cooling devices in the component compartment units of the refrigerating appliance, these devices being all connected to a common lineconnection unit, makes it possible to subdivide the refrigerating appliance in any desired manner, corresponding to the particular requirements, and to separately adjust or regulate the temperature in each individual component unit to the preferred value. Such possibility is not offered in a comparably simple manner by the conventional refrigerators of the compression or absorption type because they would require employing a corresponding plurality of individual evaporators with appertaining refrigarp o1 Surproooe 1211 1912; sq], go QIllllA Ag 'souq luaro invention several and individually insulated cooling units are employed, a refrigerating cabinet, for example a wallmounted cabinet, can readily be subdivided for example into individual cabinet or compartment units, for example 5 to 10 liter boxes, or boxes having a volume of as little as 1 gallon up to several gallons, each box being individually cooled by its own Peltier block or group of blocks. Such small boxes can be universely employed in form of a modular or building-block system so that any desired number of these boxes can be put together to form a refrigerating furniture whose shape and size can be chosen by the user himself. The invention, for example affords covering a kitchen wall or part thereof with individual cooling units in form of cupboards, or the units may be used to fill wall recesses or mounting niches and the like.

The individual cooling units, separately insulated and separately installable although provided with a common current-supply unit, can be readily adapted to the specific use or purpose as far as size of the individual compartment and internal equipment are concerned. Thus for example, separately insulated cooling units can be provided for the normal-temperature compartment, for a butter compartment, a bottle or beverage compartment or the like, and each of these compartments can be adapted and equipped to a particular intended use.

The foregoing and other objects, advantages and features of the invention, said features being set forth with particularity in the claims annexed hereto, will be apparent from, and will be further described in, the following with reference to the embodiments of appliances according to the invention illustrated by way of example on the accompanying drawings in which:

FIG. 1 is a front view and FIG. 2 a lateral view of a refrigerator;

FIG. 3 shows schematically a cross section through one of the cooling units that form part of the refrigerator according to FIGS. 1 and 2, the section being taken along the line C-D in FIG. 4; FIG. 4 is a section taken at a right angle to that of FIG. 3 and extending along the line A-B in FIG. 3;

FIG. 5 is an electric circuit diagram of a refrigerator according to the invention.

FIG. 6 is a modified circuit diagram of such a refrigerator; and FIG. 7 illustrates in perspective the details of one of the Peltier blocks used in apparatus according to FIGS. 1 to 6.

The refrigerator shown in FIGS. 1 and 2 is essentially a piece of furniture which comprises four modular cabinet units 1 placed upon a common mounting base 2 and each provided with a door or lid 3 hinged along the lower horizontal edge of the compartment unit so that it can be turned downward as indicated by a brokenline arrow in FIG. 2. The interior of each compartment unit 1 thus forms a cooling space separate from the spaces of the other units and accessible separately therefrom.

The mounting base 2 is hollow and contain the linei connector components common to the Peltier devices with which the respective compartments units 1 are individually equipped.

As apparent from FIGS. 3 and 4 for one of the individually insulated cooling units, each unit is essentially a box structure with an inner cell space 21 for receiving the products to be cooled, an external shell 22 which like the inner shell may consist of sheet metal, and a heat-insulating substance 23 such as glass wool which fills the interspace between the inner and outer shells. At the side facing the door, the cell is connected with the outer shell 22 by a sealing frame structure 24 of solid material having poor heat conductance which carries a rubber basket 25 and a magnet 26. The magnet serves to keep the door closed. The door comprises an inner sheet-metal portion 27, an outer shell 28 of sheet metal and an intermediate insulation 29.

A Peltier battery serves for cooling the cell space 21 of the box structure. The Peltier battery comprises two Peltier blocks 30 and 31, each composed of a multiplicity of individual thermocouples whose hot junctions are all located on one side of the block and whose cold junctions are all located on the other side of the block. The design and the particular details of the Peltier blocks are not essential to the present invention. They may correspond, for example, to the Peltier blocks described in the copending application of Heinz Miiller Serial No. 164,079 filed January 3, 1962, and the patent of Wolfram Blumentritt, No. 3,111,813, both assigned to the assignee of this application. With respect to suitable materials for the Peltier couples and the design of the Peltier blocks reference may also be had to US. Patent 2,978,570 and to the copending application Serial No. 150,701 of W. H'anlein for Thermoelectric Battery and Method of Its Production, filed November 7, 1961. The two Peltier blocks 30 and 31 have their coldjunction sides facing each other and in heat conducting face-to-face relation with a heat conducting body 32 of aluminum which forms part of a cooling bracket 33. The design and performance of the two Peltier blocks in relation to the intermediate heat conducting body 32 are in accordance with the cooling apparatus illustrated and described in the above-mentioned patent of Wolfram Blumentritt, No. 3,111,813, and corresponds to FIG. 3 of that application. The cooling bracket 33 straddles the cell 21, being in good heat conducting contact with the rear wall 34 and the two. side walls 35 and 36 of the cell. The two hot-junction sides of the respective Peltier blocks 30 and 31, facing, away from each other, are connected with respective heat exchangers 37 and 38 of which eachis provided with cooling fins 39. The heat exchangers 37 and 38 are joined with each other by means of screw bolts 40 which clamp them against the Peltier blocks and against the intermediate heat conducting body 32, thus pro-stressing the assembly and maintaining a reliable heat conducting contact between the mutually adjacent parts. The heat conducting body 32, however, is provided with a thin insulating coating so as to be electrically insulated from the two Peltier blocks without appreciably reducing the heat transfer from the blocks to the body 32. A similar thin insulating coating may be provided between the heat exchangers 37, 38 and the Peltier blocks to prevent electric short circuits while permitting the desired heat transfer. The Peltier blocks 30 and 31 and the parts of the heat exchangers 37 and 38 clamped together therewith by means of the bolts 40 are built into a recess in the rearward insulation of the compartment structure. The cooling fins 39 of the heat exchangers are arranged in a venting shaft at the rear of the box structure. The upper cover 43 of the box structure extends rearwardly over the venting shaft 41 where it is provided with openings 44 for the passage of the cooling air ascending through the venting shaft and thereby cooling the fins 39.

In the circuit diagrams of FIGS. 5 and 6 only three of the individual cooling compartments are illustrated and denoted by 51, it being understood that any number of such compartments can be analogously connected with the same current-supply unit. Furthermore, in FIGS. 5 and 6 the Peltier assembly of each compartment unit 51 is schematically shown only and is denoted by 52.

According to FIG. 5, several compartment units 51. as described above with reference to FIGS. 1 to 4, each containing its own Peltier battery 52, are connected to a common line-connector unit 55 which, as explained above, is accommodated in the mounting base 2 of the cabinet structure exemplified in FIGS. 1 and 2. The Peltier batteries 52 in FIG. 5 are all connected in series with each other across the output terminals 53 and 54 of the line-connector unit 55. The unit 55 comprises a transformer 56 whose primary winding is connected to a cord 57 and plug for attachment to an outlet of a utility line. The secondary winding of the transformer 60 comprises rectifiers 58 and filter means here represented by a reactor coil 59.

Connected between the secondary winding 60 and the rectifiers 58 are the contacts 61, 62 of a selector switch. In the illustrated switch position a, the selector switch is set for energizing the three illustrated cooling-box units 51. If only two such box units are employed, the switches 61, 62 are to be placed into the mid-position b. If only one box 51 is to be energized from the unit, the switches 61, 62 are to be set to the broken-line position c. It will be understood that any number of tap positions may be provided for the transformer secondary 60 in order to make the power-supply unit 55 adaptable to a greater number of units so that one and the same power supply unit can be used regardless of the number of box units initially connected thereto or subsequently added to the refrigerating equipment of a home, for example.

The circuit diagram according to FIG. 6 is substantially similar to that of FIG. 5 as is apparent from the use of the same reference numerals for respectively corresponding circuit components. According to FIG. 6, however, rectifiers 63 are built into each box unit. The Peltier assembly 52 together with the rectifiers 63 of each unit is connected in parallel relation to the corresponding components of each other unit to the same secondary voltage of the transformer and of the filtering means 59 which all box units have in common. One pole of the Peltier assembly may be connected to the housing for forming a ground potential, so that when a multiplicity of boxes are employed, single-pole connections are sufficient if the housings of all boxes are connected with one another.

The line-connector units 55 as shown in FIGS. 5 and 6 can be so dimensioned electrically that they are suitable for energizing any devices that may be employed in a household and are to be operated with direct current. A power outlet 70 is provided on unit 55 for this purpose. Such household devices may be those that operate with Peltier blocks, for example selectively operable cooling and hot plates, cold or hot water storage containers, or other direct-current devices of any type.

By virtue of the fact that according to the invention a refrigerating appliance of the size heretofore customary is subdivided into individual small or miniature boxes or cabinets, the resulting universal possibility of subsequent enlargement greatly reduces the cost of initial investment to the customer or user because he can start for example with only one or two normal cooling-compartment units, leaving it to the future, to subsequently enlarge the refrigerating furniture by addition of bottle compartments, butter compartments or the like. A particular advantage of a refrigerating appliance according to the invention resides in the fact that the different products are aromatically separated to a greater extent than in refrigerator cabinets of the conventional type in which a single cooling chamber is subdivided by partitions into individual compartments. Furthermore, the stored objects in an appliance according to the invention, are accurately kept at the desired or most favorable temperature in a particularly simple manner and are accessible, independently of the products stored in other compartments, through the door or lid with which each individual box is equipped.

The miniature boxes of which a refrigerating appliance according to the invention is composed can be given respectively different dimensions depending upon their particular purpose. However they are preferably so designed that all Peltier assemblies in the individual cooling units constitute single, or, if desired, multiple structural units which are all of the same design, for example are all rated for 1 volt and 12 amperes. If preferred, all individual box units can then be equipped with a single thermoelectrical'unit of the Peltier assembly having the rating adopted and kept uniform for all units. However, the system of unit boxes may also be so designed that some of the boxes are equipped with a plurality of Peltier base units, for example rated for 2 volts and 12 amps. In conjunction with mixed units of the latter type, it is preferable to make the electric-line connection unit of the system selectively switchable in order to per mit the connection and operation of several series connected Peltier assemblies, each appertaining to one of the respective boxes. According to another embodiment of such a system, the Peltier unit in all boxes has the same rating and rectifiers are mounted together with the Peltier assemblies so that a plurality of such boxes, all requiring the same operating voltage, are connected in parallel relation to a transformer with a common filter or smoothing device.

As exemplified by the embodiments above described, it is essential to the invention that a single current-supply unit for connection to the power supply line is common to a plurality of direct-current consuming thermoelectric cooling units to be operated selectively or simultaneously. It is particularly advantageous to give such a line-connection unit a rating such that it can be universally employed wherever direct current is needed or desirable for use with household appliances. Consequently, the dimensioning and connecting possibilities of the line-connection unit are preferably chosen so that not only a plurality of cooling boxes equipped with Peltier blocks are connected thereto, but that also other household appliances operating with Peltier cooling devices can be selectively energized from the same power-supply unit, for example bottle cooling devices, cooling or heating plates, cold or hot water storage containers or the like. The same power supply unit, preferably equipped with an outlet to make direct current available for other purposes, can then also be used for the operation of other direct-current consuming devices as may be employed in the household although they are not equipped with Peltier cooling devices.

An example of a single Peltier block as incorporated in FIGS. 1 to 6 is shown in FIG. 7. The Peltier block is composed of thermocouples. Each individual couple is formed of two thermoelectrically different legs 71 and 72 consisting, for example, of semiconductor material having p-type conductance in one leg and n-type conductance in the other leg. The two legs 71 and 72 of each couple are electrically and thermally connected with each other by a bridge plate 74 of good conducting metal such as copper. Each of the two legs is further connected at the opposite end with the leg of an adjacent thermocouple by a similar bridge plate 73 of good conducting material. In the illustrated embodiment, a large number of such couples are electrically connected in series with each other and the terminal plates of the entire series are provided with electric leads 75 and 76 respectively for passing an electric current through the entire series of thermocouples in order to then produce hot junctions at the plates 74 and cold junctions at the plates 73. The hot-junction plates 74 have their top surface located in a single plane, and the cold-junction plates 73 have their bottom surface located in a single plane parallel to that of the hot-junction plates. The p-type material for the thermocouples may consist of example of a solid solution of bismuth telluride and antimony telluride. The n-type material for the thermocouple may consist of a solid solution of bismuth telluride and bismuth selenide. The front faces of the couple legs 71 and 72 are made solderable, for example with the aid of ultrasonics, by electroplating with iron copper or nickel, or by vaporizing iron copper or nickel or other solderable metal onto these faces. The coatings then produced are then soldered together with the abovementioned plates 73 and 74. It will be understood, however, that the particular thermoelectric materials used for the thermocouples are not essential to the invention proper and that various other known substances are available for this purpose. Furthemore, the Peltier blocks may be given an arrangement and design different from the one described above with reference to FIG. 7.

Upon a study of this disclosure, it will be obvious to those skilled in the art that the invention permits of Various modifications with respect to individual components and arrangement of the block units and the power-supply unit, and hence can be given embodiments other than particularly illustrated and described herein, without departing from the essential features of the invention and within the scope of the claim annexed hereto.

We claim:

A cooling appliance, comprising a plurality of mutually separable and thermally insulated cooling units having respective chambers for operation at different temperatures and being individually mountable in a multitude of relative positions, common mounting means for holding said cooling units in one of a number of modular formations forming a single unitary piece of furniture,

said units having individual independently accessible opening means, separate Peltier-couple assembly means connected to each of said units for cooling the respective chambers, and a line-connection power supply in said mounting means common to said cooling units ad electrically connected to all of said Peltier-couple assembly means, said individual Peltier-couple assembly means in the cooling units each having rectifier means, connector means for connecting each Peltier-couple assembly means parallel to the components of the other assembly means, said power-supply having a transformer and a filter to which all of said assembly means are electrically connected.

References Cited by the Examiner UNITED ROBERT A.

STATES PATENTS Forbes 62441 Shipman 62265 Luneke 62326 Lindenblad 623 Danielson 623 Becket 623 Roeder 623 Gaysowski 623 OLEARY, Primary Examiner.

WILLIAM J. WYE, Examiner, 

